<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div class="box">
        <div class="left">1</div>
        <div class="right">2</div>
       
    </div>
    <div class="we"></div>
</body>
</html>
<style>
    .box{
        display: flex;
        
    }
    .left{
        background-color: red;
        width: 200px;
        height: 200px;
    }
    .right{
        width: 200px;
        height: 200px;
        background-color: black;
    }
    .we{
        width: 100px;height: 100px;background-color: darkblue;
    }

</style>
<script>
    let arr = [1,2,34,345,3]
    let narr=[34,34,34,34,3,4]
    narr.push(...arr)
    console.log(narr);
</script>